Effects of fertilization methods in wheat on gases emission and environmental benefit in Mollisols of Northeast China

Aims Many previous studies have focused on crop yields, but there is a knowledge gap regarding the environmental benefits of phased fertilization and organic substitution. To study the effects of phased fertilization and organic substitution on soil gas emissions and spring wheat yields, a field experiment was conducted using Mollisols. Methods Five treatments were set up: conventional nitrogen application (CF); no nitrogen application (N0); one-time (N1), two-stage (N2) and three-stage (N3) application of chemical nitrogen based on 25% of chemical nitrogen being replaced by organic fertilizer. The changes in NH3 volatilization, N2O and CO2 emissions, soil-related carbon and nitrogen invertase activities and soil carbon and nitrogen contents under different treatments were analyzed and compared. Result The results showed that N1 had the best emission reduction and yield increase effects. Compared with CF, N1 reduced NH3 volatilization, N2O and CO2 emissions accumulation by 28.94%, 10.29% and 17.21%, respectively, and increased spring wheat yield by 21.33%. Compared with N2 and N3, N1 could better reduce soil urease, nitrate reductase, catalase and β-glucosidase activities, reduce the conversion rate of urea and organic carbon, increase the content of NH4+-N in soil, and reduce the NH3 volatilization rate and N2O and CO2 emissions rates. Conclusions Comprehensive analysis showed that the N1 treatment had the best effect on reducing the soil gas emission rate, emission reduction rate and environmental cost as well as on increasing yield.